Yes, it was probably your seat...
The problem was that your seat was connected to an X2 train, that's why you had a sh*tty ride. Next time try riding in a seat and row that's connected to a Tatsu, Ninja or Twisted Colossus train and see if you have a better experience.
It surprises me, the only 4D coaster i've ridden is Eejanaika at Fuji-Q and it has the new S&S trains too. It runs pretty smooth. It's a wild ride, but it wasn't painful or rough for us anyway. We sat in different positions on the train. Love that ride!